Cardiac failure occurs when the heart is unable to deliver a sufficient supply of oxygenated blood to serve the metabolic needs of the peripheral tissues. There are a large number of primary causes of failure, virtually all of which may be accompanied by myocardial inflammation as an "adaptive" process that may actually do more harm than good. Autoimmunity to cardiac antigens, cardiac myosin in particular, may develop during inflammatory heart disease in humans and experimental animals after a wide range of infections, ischemic damage and cardiotoxic drug treatment. A powerful model of experimental autoimmune myocarditis (EAM) has been developed that is initiated by immunization of susceptible strains of mice with purified myosin in complete Freund's adjuvant. Much has been done during the past decade to characterize the EAM model and it is known to be (i) mediated, at least initially, by CD4+ T cells and (ii) biphasic, with a proinflammatory phase followed by a phase of repair and fibrosis. Our recent work has focused on the basic mechanisms of EAM pathogenesis with an emphasis on the prevention and treatment of autoimmune myocarditis by restoration of peripheral immune tolerance and by angiotensin converting enzyme inhibition. We have assembled a research team with expertise in the pathology, genetics, immunology, and molecular and cellular biology of EAM, and propose to continue our work with the following Specific Aims: (i) to elucidate the molecular pathogenesis of the inflammatory and resolution phases of myosin-induced EAM, with a focus on the functional immunology of these processes, (ii) to investigate the antigen specificities of the immune responses in EAM and the potential of peripheral tolerance induction for the treatment of ongoing disease and (iii) to explore the role of the renin angiotensin system in EAM pathogenesis.